Portable concrete mixing plants



March 22, 1966 G. MAXON, JR 3,24L1

PORTABLE CONCRETE MIXING PLANTS Filed Aug. 26, 1964 s Sheets-Sheet 1 arch 22, 1966 G. MAXON, JR 3,241,821

PORTABLE CONCRETE MIXING PLANTS Filed Aug. 26, 1964 5 Sheets-Sheet 2 e mJwfiwd GZenway Max:721, Jr:

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March 22, 1966 G. MAXON, JR 3,241,821

PORTABLE CONCRETE MIXING PLANTS Filed Aug. 26, 1964 5 Sheets-Sheet 3 March 22, 1966 s. MAXON, JR 3241 821 PORTABLE CONCRETE MIXING PLANTS Filed Aug. 26, 1964 5 Sheets-Sheet 5 [lllllllll ||H| llllllllllllilllllifi 1 MIN I United States Patent I 3,241,821 PORTABLE CONCRETE MIXING PLANTS Glenway Maxon, Jr., 1830 E. Kane Plane, Milwaukee, Wis. Filed Aug. 26, 1964, Ser. No. 392,103 6 Claims. (Cl. 259-171) This invention relates to improvements in concrete mixing apparatus of the type disclosed in my Patent No. 3,021,122, issued February 13, 1962, wherein a rotatable mixing drum is supported for tilting motion between a mixing position and a discharging position in which the rear portion of the drum is raised substantially above the elevation that it has when in its mixing position.

In the concrete mixing apparatus of the aforesaid patent the drum was mounted on a cradle which was in turn supported on links whereby the drum was carried bodily forwardly as it was being tilted to its discharging position, so that the drum could be discharged directly into the body of a transit truck even when the truck was parked some distance outwardly from columns that supported the mixing plant. The drum carrying structure shown in that patent was, however, substantially wide, and while suitable for many permanent installations it did not lend itself well to portable mixing plants of high capacity.

Portable contrete mixing plants are needed for most major highway paving projects and for many dam and other construction projects where a high capacity central mixing plant must be established near the project site for only a relatively short period of time. It is desirable that the components of a portable mixing plant be transportable over the highways without special arrangement other than an over-width highway permit, and it is also desirable that the plant be movable as a few major units which do not require extensive dismantling and reassembly at each move. To meet these desiderata it is necessary that the mixing plant have an over-all width that is not in excess of 12 ft. Constructed as illustrated in my aforesaid patent, a mixing plant that was not over 12 ft. wide would necessarily have a capacity of 4 cu. yds. or less, which is too small for really efiicient operation on a major project.

With the foregoing in mind, it is a general object of the present invention to provide a mixing plant of the character described which is substantially narrower for a given drum capacity than that illustrated in my aforesaid patent, and which can have a capacity of as high as 8 cu. yds. within an overall width of 12 ft.

It is also an object of the present invention to provide a high capacity portable concrete mixing plant of the character described which comprises a mixing drum that is mounted for combined tilting and bodily fore-andaft motion in the manner disclosed in my aforesaid patent, and which mixing drum and its supporting structure can be mounted on a trailer that is within allowable height and width limits for highway transport under an easily obtainable over-width permit although having a capacity of up to 8 cu. yds.

Thus it is a further object of this invention to provide a reduction in the overall width of mixing plants of the character described, as compared with previous structures of that type, without significantly increasing the height of the plant, to thus achieve a higher mixing capacity for a given width of plant structure.

It is still another object of this invention to provide a portable concrete mixing plant which is well adapted to movement on the highways and which, because of its inherent compactness, requires little dismantling and reassembly for movement from one location to another.

It is also an object of this invention to provide mixing 3,241,821 Patented Mar. 22, 1966 apparatus that is sufiiciently compact so that a large capacity mixer embodying the principles of this invention can be installed in an existing stationary batching plant of small capacity, thus making it possible to substantially increase the capacity of the existing installation without the need for rebuilding its fixed structure.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a view in side elevation of a trailer upon which is mounted concrete mixing apparatus embodying the principles of this invention;

FIGURE 2 is a side elevational view of a mixing plant that incorporates the trailer unit shown in FIGURE 1, the mixing drum being shown in its mixing position;

FIGURE 3 is a view similar to FIGURE 2, but showing the drum in its discharging position;

FIGURE 4 is a plan view of the mixing apparatus;

FIGURE 5 is a front elevational view of the mixing apparatus; and

FIGURE 6 is a more or less diagrammatic side view of the mixing apparatus showing the extreme discharge position to which the drum can be tilted with the employment of a double acting booster cylinder.

Referring now more particularly to the accompanying drawings, the numeral 5 designates generally a highway trailer upon which there is mounted mixing apparatus 6 embodying the principles of this invention. The trailer chassis comprises a pair of elongated horizontal frame members 7 and has wheels 8 at its rear. In transit, the front end of the trailer is carried by a tractor 9 by which the vehicle is towed. At an operating site, the trailer is lifted bodily and mounted on a suitable foundation structure 14 by which the load of the equipment is taken off of the wheels 8 and by which the mixing apparatus is held at a substantial elevation above the ground.

The mixing apparatus comprises, in general, a drum 11 which is rotatably carried in a substantially U-shaped cradle 12 and which has a coaxial charging inlet 13 in its rear and a coaxial discharge outlet 14 in its front. It will be noted that the front of the mixing apparatus is at the rear of the trailer, and henceforth all references to fore-and-aft directions will be related to the mixing apparatus.

A power plant 15 mounted at the opposite end of the trailer from the mixing apparatus provides a source of hydraulic pressure fluid for hydraulic motors 16 which are mounted on the cradle 12 to rotatably drive the drum.

When the apparatus is installed at an operating location, a cement batcher 17 is mounted on the trailer frame with its hopper projecting upwardly above the rear portion of the drum and its outlet 20 adjacent to the charging inlet 13 in the rear of the. drum. Aggregate is brought to the charging inlet by means of an endless conveyor 21 which extends obliquely rearwardly and downwardly from the charging inlet.

The fixed structure on the trailer frame by which the mixing apparatus is supported comprises a pair of opposite, generally upright A-frames 23, one at each side of the chassis, disposed behind the cradle 12. The mixing drum and its cradle are suspended from the A-frames for tilting and bodily fore-and-aft motion by means of upper supporting links 24, which are pivotally connected to the A-frames and to the cradle 12. Lower guide links 25, which are pivotally connected between the cradle and the trailer frame, effect tilting of the drum concomitantly with its fore-and-aft bodily motion. In addition to sup porting the drum and its cradle, the A-frames cooperate with a pair of upright columns 26 to support the batcher 17, and can also support the front end portion of the conveyor 21.

It will be observed that the axis of the mixing drum lies in the same vertical plane that contains the longitudinal center line of the trailer chassis, and consequently the width and height of the mixing drum and its supporting structure will control whether or not the equipment can be transported on the highways. According to the present invention, the fixed and movable structure which supports the drum for tilting and rotation has an overall Width that is only slightly greater than the drum diameter, and an overall height only slightly greater than its Width. Thus the cradle 12, the drum rotating motors 16, the A- frames 23, the upper supporting links 24 and lower guide links 25, and hydraulic cylinders 28 and 29 by which the drum is tilted, are all disposed within a zone defined by a pair of vertical planes which extend rearwandly parallel to the drum axis and which are contiguous to the cradle at the laterally outermost portions thereof and to the outer side faces of the A-frames. By reason of this arrangement, a supporting structure 12 ft. wide and less than 14 ft. 6 in. high, overall, in transit condition, can carry a drum having a ft. 6 in. diameter. Such a drum can have a capacity of 8 cu. yds. or more.

The U-shaped cradle 12 that carries the drum for rotation and for tilting motion has substantially straight upright arms 30 and a substantially straight bottom or bight portion 31, all of which can be fabricated box-section members. The upper end portions of the arms, which are substantially on a horizontal line with the drum axis, can be cut back at their inner faces, as at 32, to provide additional clearance for the drum.

The drum has a circumferential ring gear 33 around its medial portion, as is conventional, but in this case the ring gear provides a circumferential shoulder 34 that faces in one axial direction and cooperates with guide rollers 35 and 36 on the cradle. A circumferential flange 37 around the drum, spaced in said axial direction from the ring gear, provides an oppositely facing circumferential shoulder 38 that also cooperates with the guide rollers to confine the drum against tilting and axial motion relative to the cradle. The drum is rotatably supported on the cradle by means of bearing rollers 39 that track on the flange 37. Preferably there is a guide roller 35 at the top of each arm of the cradle, the axes of said guide rollers being substantially on a horizontal line through the drum axis. Another guide roller 36 is mounted at the center of the bottom or bight member 31 of the cradle for rotation on a vertical axis intersecting that of the drum. The bearing rollers 39, which are of course freely rotatable on axes paralleling that of the drum, are mounted on gussets 40 in the junctions of the upright arms 30 of the cradle with its bottom member 31, at the rear of the cradle.

It will be seen that the cradle has an overall width that is only slightly greater than the diameter of the drum, owing to the structure just described whereby the drum is mounted for rotation on the cradle.

The hydraulic motors 16 which rotatably drive the drum are mounted on top of the bottom member 31 of the cradle, each closely adjacent to one of the upright arms 30, so that they are located entirely within the confines of the cradle. As is conventional, a pinion 41 on each motor meshes with the ring gear 33 to provide a driving connection between the motor and the drum.

Each of the A-frames 23 comprises a pair of upwardly converging box section legs 42 and 43 which are rigidly secured at their lower end portions to the longitudinal frame members 7 of the chassis. The front leg 42 of each A-frame is upwardly and rearwardly inclined and has its lower end directly behind the cradle. The rear leg 43 is inclined forwardly and upwardly and has its upper end portion connected to the top of the front leg by means of a rigid cap member 44 which carries a fixed pivot support 45. A rigid transverse member 46, connected to the A-frames at their tops, bridges the two A-frames to steady them laterally. It will be observed that the rear porion of the mixing drum remains well clear of the transverse member 46 during tilting of the drum to its discharging position, owing both to the bodily forward motion imparted to the drum and to the rearward inclination of the front A-frame legs 42.

The rear leg-s 43 of the A-frames are substantially wider than the front legs 42, in the direction transverse to the drum axis. Since both legs have their laterally outer faces on a vertical plane parallel to the drum axis, the rear leg of each A-frame extends inboard farther than the front leg. Although the front legs of the A- frames bear most of the load of the mixing drum and its contents, no bracing or reinforcement of them is needed, other than that provided by the rear legs, because the load forces on the front legs are mainly in endwise compression.

The upper supporting links 24, by which the cradle 12 is suspended from the A-frame, comprise the opposite arms of an inverted U-shaped carrier, being connected at their upper ends by a transverse box section member 47. At their upper ends the upper supporting links are connected to the fixed pivots 45, which are of course disposed on a common horizontal axis transverse to that of the drum and spaced above the rear portion of the drum. At their lower ends the supporting links have pivotal connections 48 to the arms of the cradle, near the tops thereof, which connections define a common horizontal axis parallel to that of the upper fixed pivots 45 and near the level of the drum axis. The pivotal connections 48 are on the rear sides of the cradle arms, and the upper fixed pivots 45 on the front sides of the front A-frame legs; hence the upper supporting links 24 are disposed entirely within the zone described above.

The lower guide links 25 are connected between the bight portion 31 of the cradle and a transverse member 50 fixed to the longitudinal beams 7 of the chassis frame. They are spaced substantially inboard from the A-frames so as to extend between the front legs 42 thereof with a substantial amount of clearance, and thus lie well within the zone described above.

For moving the drum between its discharging and its mixing positions the plant is provided with the upper and lower hydraulic cylinder means 28 and 29, respec= tively, which, as already noted, are disposed entirely within the zone described above. The upper cylinder means 28 comprises a pair of large single-acting cylinders, each pivotally connected between the rear leg 43 of one of the A-frames and its forwardly adjacent supporting link 24. The connection of each cylinder 28 to its rear A-frame leg is about midway between the top and bottom ends of the leg, and its pivotal connection to its upper supporting link is likewise intermediate the ends of the link. As pointed out hereinabove, the rear legs of the A-frames, being wider than their front legs, extend inboard farther, and the cylinders 28 are connected to the rear legs at the inboard faces of the latter. Hence the cylinders 28 are located between, but closely adjacent to, the front legs 42 of the A-frames.

Only one set of the hydraulic cylinder means 28 and 29 would be needed to effect motion of the drum between its mixing and discharging positions, but it has been found that smoother and faster tilting action can be obtained with the use of two sets of cylinder means as shown. The lower cylinder means 29 comprises a smaller booster cylinder which is pivotally connected to a cross member 25' that bridges the medial portions of the guide links 25, and to fixed strmture 52. 9L5 th chassis frame that is below and behind the guide links, so that the booster cylinder can exert a generally upward lifting thrust upon the guide links. Since the booster cyl inder is on the longitudinal centerline of the trailer, the booster cylinder is of course disposed substantially inboard of the A-frames. Preferably the booster cylinder is double acting, so that it can be used to swing the drum in both directions through a toggle position in which the guide links 25 are aligned with the pivotal connections 48 between the supporting links and the cradle. Thus the drum can be tilted to the nearly vertical position illustrated in FIGURE 6, at which it provides quick and positive discharge of very viscous concrete, and can be returned very quickly to its mixing position under the combined forces exerted upon it by gravity and the booster cylinder.

Preferably the double acting booster cylinder 29 is so connected with the return hydraulic duct from the motors 16 that a certain amount of down force is exerted by the booster cylinder when the drum rotating motors are in operation, to thus insure against any possibility of the drum being tilted out of its mixing position by gravity forces.

It will be observed that the A-frames 23, the upper supporting links 24, the guide links 25, the cradle and drum, and the hydraulic motors 16 and the cylinder means 28 and 29 can all remain assembled while the plant is being transported from place to place. Hence erection of the plant involves only placement of the trailer on the foundation structure 10, erection of the batching hopper 17, and assembly of the endless conveyor 21. As shown, the batching hopper 17 comprises a complete trailer unit in itself, so that its assembly onto the trailer 5 that carries the mixing drum can be very readily accomplished. Because the foundation structure need not exceed an overall width of 12 ft., it too can be readily transported (as on a flat bed trailer) without the need for disassembly. The endless conveyor 21 can be transported on the trailer that carries the mixing drum, stowed between the longitudinal frame members 7 thereof, in accordance with the teachings of my copending application Serial No. 307,083, filed September 6, 1963, now Patent No. 3,151,849.

From the foregoing description taken together with the accompanying drawings it will be apparent that this invention provides a readily portable concrete mixing plant of substantially high capacity which can be very quickly erected and dismantled and which can be trans ported over the highways under a readily available overwidth permit.

What is claimed as my invention is:

1. Concrete mixing apparatus of the type having a drum that is constrained to rotation on its axis in a cradle having upwardly projecting arms which embrace the medial portion of the drum, and wherein link means carried :by fixed structure suspends and guides the cradle for combined tilting and bodily fore-and-aft motion between a mixing position of the drum in which the drum axis is horizontal and a discharging position in which a discharge opening in the front of the drum is lowermost, said mixing apparatus being characterized by the following:

(A) the fixed structure comprises a pair of upright supporting members behind the cradle, one on each side of the rear part of the drum, said supporting members being disposed within a zone defined by a pair of vertical planes which extend rearwardly parallel to the drum axis and which are contiguous to the laterally outermost portions of the cradle;

(B) the link means comprises (1) a pair of upper supporting links, each pivotally connected to one of said supporting members and to an arm of the cradle, said upper supporting links being disposed wholly within said zone, and

(2) guide link means disposed wholly within said zone and pivotally connected to the fixed supporting structure and to the lower portion of the cradle;

(C) a pair of hydraulic cylinders by which the drum is tilted are each connected between one of said upright supporting members and its connected supporting link, each of said hydraulic cylinders being disposed wholly within said zone.

2. Concrete mixing apparatus of the type having a drum that is constrained to rotation on its axis in a cradle having upwardly projecting arms which embrace the medial portion of the drum, and wherein link means carried by fixed structure suspends and guides the cradle for combined tilting and bodily fore-and-aft motion between a mixing position of the drum in which the drum axis is horizontal and a discharging position in which a discharge opening in the front of the drum is lowermost, said mixing apparatus being characterized by the following:

(A) the fixed structure is located entirely behind the cradle;

(B) the link means is located entirely within a zone defined by a pair of vertical planes which extend rearwardly parallel to the drum axis and which are contiguous to .the laterally outermost portions of the cradle; and

(C) hydraulic cylinder means by which the drum is tilted (l) is connected between the fixed structure and the link means and (2) is located wholly within said zone.

3. The concrete mixing apparatus of claim 2 wherein said link means comprises a pair of upper supporting links and lower guide link means, further characterized by the following:

(A) each of the upper supporting links is connected to an arm of the cradle for pivotal motion about a horizontal axis which is transverse to and near the level of the drum axis; and

(B) the hydraulic cylinder means comprises a pair of hydraulic cylinders, each pivotally connected between one cf the upper supporting links and the fixed structure for bodily rocking motion about a fixed transverse axis located behind the mixing drum.

4. Concrete mixing apparatus of the type having a drum that is constrained to rotate on .its axis in a cradle having upwardly projecting arms which embrace the medial portion of the drum, and wherein link means carried by fixed structure suspends and guides the cradle for combined tilting and bodily fore-and-aft motion between a mixing position of the drum in which the drum axis is horizontal and a discharge position in which a discharge opening in the front of the drum is lowermost, said mixing apparatus being characterized by the following:

(A) the fixed structure is located entirely behind the cradle;

(B) the link means is located entirely within a zone defined by a pair of vertical planes which extend rearwardly parallel to the drum axis and which are contiguous to the laterally outermost portions of the cradle, and said link means comprises a pair of upper supporting links and lower guide link means, each of the upper supporting links being connected to an arm of the cradle for pivotal motion about a horizontal axis which is transverse to and near the level of the drum axis;

(C) hydraulic cylinder means by which the drum is tilted is connected between .the fixed structure and the link means and is located wholly within said zone and comprises (1) a pair of cylinders, each connected between the fixed structure and one of the upper supporting links,

(2) and a booster cylinder connected between the fixed structure and the lower guide link means to provide an upward lifting force which supplements that of said pair of cylinders in lifting the rear part of the drum as it is tilted towards its discharging position,

5. The mixing apparatus of claim 2, further characterized by the following:

(A) the drum has (1) a ring gear around its medial portion which defines a circumferential shoulder that faces in one axial direction, and

(2) a flange which is axially spaced from the ring gear and which defines a circumferential shoulder that faces in the opposite axial direction toward the shoulder on the ring gear, the cradle arms having upper portions received in the space between the gear and flange whereby the arms closely embrace the drum; and

(B) guide rollers on the cradle engage said shoulders defined by the ring gear and flange to constrain the drum to rotation on the cradle.

6. Concrete mixing apparatus of the type having a drum that is constrained to rotation on its axis in a cradle having upwardly projecting arms which embrace the medial portion of the drum, and wherein link means carried by fixed structure suspends and guides the cradle for combined tilting and bodily fore-and-aft motion between a mixing position of the drum in which the drum axis is horizontal and a discharging position in which a discharge opening in the front of the drum is lowermost, said mixing apparatus being characterized by the following:

(A) the fixed structure comprises a pair of opposite A-frames, one at each side of the drum, each having (1) a front leg which has its bottom end behind and adjacent to the cradle and which is inclined rearwardly and upwardly, and

(2) a forwardly and upwardly inclined rear leg which has its top connected to the top of the front leg,

said A-frames being disposed between vertical planes which are at opposite sides of the drum axis and parallel thereto and which are contiguous to the laterally outermost portions of the cradle;

(B) the link means comprises a pair of upper supporting links, each pivotally connected to the front leg of one of the A-frames, near the top thereof and at its front face, and to one of the arms of the cradle at a location inwardly of said vertical planes; and

(C) a hydraulic cylinder for tilting the cradle is connected between each A-frame and its adjacent supporting link, intermediate the ends of .the latter, said cylinders being disposed inwardly adjacent to the front legs of the A-frames.

References Cited by the Examiner UNITED STATES PATENTS 3,021,122 2/1962 Maxon 259-171 3,151,849 10/1964' Maxon 259-'161 WALTER A. SCHEEL, Primary Examiner.

CHARLES A. WILLMUTH, Examiner. 

2. CONCRETE MIXING APPARATUS OF THE TYPE HAVING A DRUM THAT IS CONSTRAINED TO ROTATION ON ITS AXIS IN A CRADLE HAVING UPWARDLY PROJECTING ARMS WHICH EMBRACE THE MEDIAL PORTION OF THE DRUM, AND WHEREIN LINK CARRIED BY FIXED STRUCTURE SUSPENDS AND GUIDES THE CRADLE FOR COMBINED TILTING AND BODILY FORE-AND-AFT MOTION BETWEEN A MIXING POSITION OF THE DRUM IN WHICH THE DRUM AXIS IS HORIZONTAL AND A DISCHARGING POSITION IN WHICH A DISCHARGE OPENING IN THE FRONT OF THE DRUM IS LOWERMOST, SAID MIXING APPARATUS BEING CHARACTERIZED BY THE FOLOWING: (A) THE FIXED STRUCTURE IS LOCATED ENTIRELY BEHIND THE CRADLE; (B) THE LINK MEANS IS LOCATED ENTIRELY WITHIN A ZONE DEFINED BY A PAIR OF VERTICAL PLANES WHICH EXTEND REARWARDLY PARALLEL TO THE DRUM AXIS AND WHICH ARE CONTIGUOUS TO THE LATERALLY OUTERMOST PORTIONS OF THE CRADLE; AND (C) HYDRAULIC CYLINDER MEANS BY WHICH THE DRUM IS TILTED (1) IS CONNECTED BETWEEN THE FIXED STRUCTURE AND THE LINK MEANS AND (2) IS LOCATED WHOLLY WITHIN SAID ZONE. 